Uterine Anomalies - How Frequent Are They?
Frederick R. Jelovsek MD
Congenital anomalies of the uterus can cause difficulty getting pregnant as well as successfully carrying a pregnancy to full term. Just how often these birth defects occur is not well known. The uterus is formed by two tubes that come together and the joining walls dissolve to leave a single cavity for the uterus and the ends of the two tubes as the faloppian tubes. On rare occasions, the joining walls either don't dissolve or only partially dissolve. Sometimes the tubes don't even come together. The cause for this aberration is multi factorial and not just a single genetic defect.
A recent article, Nahum GG: Uterine anomalies: How common are they, and what is their distribution among subtypes? J Reprod Med 1998; 43:877-887, looked at 47 studies in the literature from 14 countries involving 573,138 women undergoing universal screening for uterine malformations. This study based on universal screening is important because there are so many reports from infertility studies and habitual miscarriage studies which have overestimated how often these anomalies occur.
There are some differences in classification of uterine anomalies, but for the most part, authors use the following categories:
Image of anomalies
By analyzing all these studies t
ogether, Nahum concluded that the incidence of uterine anomalies in different populations was as follows:
Frequency(%) of Uterine Anomalies
| Uterine anomaly | Overall population | Fertile women | Infertile women |
|---|---|---|---|
| arcuate | 7% | 6% | 8% |
| septate | 34% | 34% | 33% |
| bicornuate | 39% | 41% | 25% |
| didelphic | 11% | 12% | 8% |
| unicornuate | 5% | 4% | 11% |
| solid, absent, hypoplastic, other | 4% | 3% | 15% |
Other conclusions drawn from this analysis include:
- uterine anomalies occur in 1 in 600 fertile women
- uterine anomalies occur in 1 in 30 infertile women
- uterine anomalies occur in 1 in 200 general population women
- arcuate and septate uteri do not seem to predispose to infertility
- unicornuate uteri are associated with an increase in infertility
- bicornuate and didelphic uteri do not predispose to infertility and in fact may enhance fertility
Please note that this only refers to getting pregnant (fertility), the anomalies can often lead to recurrent miscarriages and preterm deliveries (1, 2) and in those cases may need surgical correction to enhance the chances of a full term birth.
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